Controlling means for gyro instruments



June 4, 1946. R. s. CURRY, JR

CONTROLLING MEANS FOR GYRO INSTRUMENTS Filed Aug. 15, 1942 INVENTOR R. s. CURRY, JR.

ATTORNEY instrument, and.

(Journos MEANS INSTRUMENT 50B GYRO Robert S. Curry, 3n, Baldwin, N. Y., assignor to Sperry Gyroscope Company, Inc, Brooklyn, N. Y a. corporation of New York Application August 15, 1942, Serial No. 455,007

1 This invention relates generally'to gyro instruments and particularly concerns a novel means for controlling a device operable to exert a turning moment about one of the axes of support of 3 the rotor bearing case of such an instrument; In

the embodiment of the invention illustratively depicted in the accompanying drawing, a directional gyro instrument is employed having a torque motor operable to exert a turning moment about the vertical axis of the instrument. Consequently the torque motor of the present invention may be used with an electrical signal producing, tilt responsive device as a means .for correcting tilt of the rotor bearing case of, a gyro instrument from a normal position. Y

One of the features the invention resides in utilizing the output of a secondary winding which is movable in response to tilt of the rotor bearing case to selectively energize the torque exerting device.

Another feature of the invention consists in a reversibly wound primary coil element in the instrument which cooperates with the member to form the novel controlling means.

Other features and structural details of the invention will be apparent from the following de- 8 Claims (Cl. 75)

in which a further modification of the magnetic couple for counteracting the reactive effect of secondary member in the gyro instrument.

With reference toFig. l,' the gyro instrument utilized in connection with the present inventive subject matter is shown to include an outer casing Ill having upper and lower bearings therein, as'respectively indicated at I l and ill, by which a conventional ring 13 is mounted for movement about a vertical axis. The gyro rotor healing case or frame M of the instrument is pivotally mounted in the usual fashion between the upwardly extending arms of the ring by means of bearings 95 and it which support the case for movement ings ii are supplied with three phase alternating scrlption when read in connection with the sccompg drawing, wherein Fig. 1 is a side elevation of a gyro instrument constructed in accoce with the present incurrent energy from a source 3 by way of leads 19, 2c and 25, Fig. 4. An azimuth heag indication is obtained from the described type of gyro instrument by a compass card 22 which is vention with theouter casing thereof shown in section.

Fig. 2 is a detail side elevation further shoe one form of the parts of the improved controller and the relation of the same to the vertical rin and rotor be case of the gyro instrument.

Fig. his-a view similar to Fig. 2 illustrating a modified form of the primary coil element of the controller.

Fig. 4 is a wiring die and schematic view showing the electrical connections employed in the present instance for the cooperatively functioning controller and torque exerting device.

Fig. 5 is a detail front elevation of a force counter-balancing means which may be employed in connection with the present invention.

Fig.- 6 is a view similar to Fig. 5 showing a modified form oi the counter-balancing means illustrated.

Fig. 7 is a vector diagram showing-the phase relations of the current in the torque motor emlayed in the present instance to exert the turnins moment about the desired axis of the gyro Fla. 8 ise. detail view v mounted for rotation from within the casing it.

Compass card 22 is shown as turned by vertical ring l3 by means of meshing bevel gears-23 and it, A suitable lubber line (not shown) may he provided on the surface of the window oi the instrument for comparison with the indicating face of'the com card by' the observer in determining the indication given by the instrument.

This conventional type of free gyro instrument may be converted to aninstrument having north seeking properties by slaving the same to a magnetic compass in a manner well known in the art.

In the form of'the invention shown in the drawing, the torque applying device mployed is a polyphase wound motor whose stator 26 is fixed- 1y mounted upon the vertical ring it. The conventional motor shown is of the squirrel cage induction type, the rotor 27 being annular in shape and including a plurality of spacedconducting bars therein which are electrically connected in a suitable manner. The rotor 27 is fixedly mounted on age 23 which extends inwardly from the top of the casing it. As shown. the device or motor is operable to exert a turning moment about one of the axes oi'supmrt oi the case it i Figs. cause as within the casing m hlid in the present these of which is located below the line.

3 such axis is the axis of the vertical ring l3. Th stator or the motor is polyphase wound and as shown in Fig. 4, one of the windings oi the motor ing ll oi the motor employed to spin the gyro rotor.

Thecontrolling means for the torque motor constructed in accordance with the teaching of the present invention consists of two relatively movable parts, one of which is termed a primary coil element and is designated generally at ill.

This element is a stator which in the instance shown is annular or semi-circular in form and is connected at its respective ends to vertical two sections 3| and 32, one of which is located above the horizontal line 33, Fig. 2, and the other oppositely disposed portions of the stator include a plurality of spaced pole pieces 34 across which the field flux of the element moves. The pole pieces 84 in section 3| and section 32 are wound in reverse ring IS. The stator is considered as divided into relation, as diagrammatically shown in Fig. 4

The other part of the controlling means is provided by a secondary coil member designated generally at 31 which includes a spool mounted winding 38 that is movable responsive to tilt of the case M about the othervoi the axes of support of the same or, as shown, the horizontal axis of the case, to a position in which the winding is in the path of the field flux of either one of the primary element sections. The spool mounting for the secondary winding member is indicated at 39, the same being fixed on an arm to which extends from the side of the rotor bearing case M, Fig. 2. In utilizing the novel controlling means in the present instance, the output of the secondary winding member is supplied to selectively energize the other of the windings of the torque motor by way of leads ii and 42. The other winding of the torque motor is indicated at B3 in Fig. 4.

In the modification of the invention shown in Fig. 3, the stator of the primary element is constructed to include only four curved pole faces, two of which are indicated at 8| and 32'. In a gyro instrument where a large precessional force is required, an amplifier may be inserted between the pick-up secondary coil member and the selectively controlled winding 43 of the torque motor.

energy is induced ln'the winding of the secondary.

member a'reactive force is electrically produced which tends to oppose movement of the member.

As shown, such counterbalancing means is a var-- iable reluctance magnetic couple consisting of a magnetic permeable core 44, Figs. 5 and 6, which is fixed to the side 01' the vertical ring l3 and in-- eludes a central elliptical opening is. A bar shaped permanent et or disc-shaped magnet (as respectively indicated at 36 and 81 in Figs. 6 and 5) is fixedly mounted on an extension of one of the trunnions supporting the rotor bearing case ll. Normally the magnets extend along the major axis of the elliptical opening in the core so that the reluctance in the magnetic circuit provided by the parts is a maximum. As tilt of thecase occurs, the magnets 48 or 41 are progressively moved correspondingly to a position lowering the reluctance in the magnetic circuit. In this manner a decentralizing torque is produced about the axis of the case which opposes or counterbalances the reactive centralizing torque produced on the secondary member and the consequent disturbing effect of the same on the gyro instrument.

In Fig. 8, the counteracting magnetic couple is shown to include a fixedly mounted horse-shoe type magnet 68 and a magnetically permeable core 48' which in this event is mounted to move towards the olefaces of the magnet when the gyro rotor case tilts from a normal position. The secondary member of the controller acts as a pick-off which produces a signal upon tilt of the case from a normal position about one of its axes. The reactive eflect of the pick-off or secondary member on the gyro instrument is counteracted by the torque exerted by one of the disclosed forms of magnetic coupling.

It will be understood that the selectivity of the controller results from the fact that the phase of the voltage induced in thesecondary member is reversible and is determined by the position of the secondary winding with respect to the primary coll element. A vector diagram of an instantaneous voltage current relationship in the respective windings oi the torque motor in the electrical arrangement of the parts shown in Fig. 4 is indicated in Fig. 7. In this figure the 120 displaced voltage vectors V01, V0: and V0: are representative of the respective line voltages in lines I, 2 and 3, or leads I8, 2d and 2|. The voltage vectors V01 and Van at the instant chosen are vectorially combined to obtain the resultant voltage vector V21 which is the same asthe vector V representative of the voltage supplied the primary coil element of the control means. The. corresponding voltage vector Vs of the secondary coil member is shown as 180 phase displaced from that of the primary coil element. The current voltage vector V. or the secondary coil memher is shown a 180 phase displaced from thatof the primary coil element. The current vector Is of the secondary coil member or Io of the winding 43 is shown as lagging the voltage vector by the phase angle a which is determined by the resistance and inductance constants of the circuit. The torque motor winding 49 is energized through line tor lead 2!, and the current vector Ice for the line or I: for the winding lags the vector V03 by the controlled phase angle a. Vectors I: and It: and consequently the resultant flux the diagram at L or -I.

As many changes could be made in the above construction and many apparently'widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the above description or shown in the accompanying drawing shall be interpreted as illustrative and not in a limiting sense.

What is claimed is:

1. In a gyro instrument having a rotor frame mounted with freedom about two mutually perpendicular axes, a pick-0H member producing a signal upon displacement of the frame from a normal osition about one of its axes and having a reactive eflect on the gyro instrument, and a magnetic couple for exerting a torque about the axis of the pick-off member to counteract the reactive effect 01' the pick-off member on the instrument.

2. In a gyro instrument having a rotor frame mounted with freedom about two mutually perpendicular axes, means for exerting a torque about one of the axes of the frame, a pick-oil member responsive to tilt of the frame about the other of its axis for controlling operation of said torque exerting means, said pick-oft member having a reactive effect on the gyro instrument, and a magnetic couple for exerting a torque about the axis of the pick-off member to counteract the reactive eflect of the pick-oil member on the instrument.

3. A gyro instrument as claimed inclaim 1, in which the magnetic couple comprises a permanent magnet mounted for movement responsive to tilt of the frame and a fixedly mounted magnetically permeable core having an elliptical opening therein in which said magnet moves.

4. Means for reducing deviation of a gyroscope due to resistance to precessional movements about an axis, comprising a permanent magnet and a flux conducting member adjacent thereto, one of which is mounted to turn with the gyroscope about said axis and the other of which is fixed with respect thereto, the air gap between said conducting member and magnet changing with relative movement therebetween to render the same effective to exert a decentralizing force on the gyroscope.

5. In a gyroscopic instrument having a rotor bearing frame, a casing, a ring supporting the frame for movement relative to the casing about two mutually perpendicular axes and electrical means for exerting a torque about one of the axes of the frame having a winding mounted on the ring; a coil connected to directlysupply energy to the winding of the torque exerting means mounted on the frame to move in a defined path about the second of the axes thereof, a wound stator mounted on the ring producing two magnetic fields along the path of movement of said coil that flow in opposite directions from a zone in said path. and means for energizing said stator, said coil being normally positioned in said zone in which it links both fields of the stator equally to provide a zero output and being movable in its entirety to be linked by one or the other of the fields alone to provide an output whose phase sense depends on the direction of movement of the coil from its normal position and whose amplitude is sufficient to operate the torque exerting means.

6. A gyroscopic instrument as claimed in claim 5, including means for counterbaiancing the coercive force produced on the frame when the coil provides an output.

7 A gyroscopic instrument as claimed in claim 5, in which said wound stator includes a, plurality of pole pieces in mutually facing relation situated on opposite sides of said coil and extending substantially parallel to the axis of the frame about which the coil is mounted to move.

8. A gyroscopic instrument as claimed in claim 5, in which said torque exerting means is a polyphase wound motor one of whose windings is directly energized by the output of said coil.

ROBERTS. CURRY. JR. 

